SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
Like DVFS, dynamic power switching (DPS) is a power-management technique intended to reduce the active power consumption of a device. However, whereas DVFS reduces dynamic and leakage power consumption, DPS reduces only leakage power consumption, at the expense of a slight overhead in dynamic power consumption.
With DPS, the system switches dynamically between high- and low-consumption system power modes during system active time. When DPS is applied, a processor or system runs at the highest OPP (maximum frequency and voltage) to complete its tasks quickly, followed by an automatic switch to a low-power mode for minimum power consumption. DPS is useful when a real-time application is waiting for an event. The system can switch into a low-power system mode if the wake-up latency conditions allow it.
This technique consists of maximizing the idle period of the system to reduce its power consumption.
The values in Figure 3-17 are hypothetical. They are meant only to clarify the concept and do not represent valid test results on the device.
Figure 3-17 compares the behavior of power consumption for the same operation of the device without DPS (see the left side of the figure) and with DPS (see the right side of the figure). When operating without DPS, the device has a constant leakage current in idle mode. By using DPS, the system reduces the leakage current to 0. However, the transitions between system power modes may require storing the information before entering a low-power inactive state and restoring the information after a wake-up event (see Figure 3-17). This results in additional dynamic power consumption, referred to as transition overhead (see Figure 3-17). Transition overhead must be considered for a DPS operation.
For efficient deployment of DPS techniques, it is necessary to predict dynamically the performance requirement of the applications running on the processor. The DPS controller must account for the overhead of wake-up latencies related to domain switching and ensure that they do not significantly affect the performance of the device. Even with transition overhead, the user can identify an optimal idle-time limit, after which the DPS is useful for dynamic power saving.